1. Field of the Invention
The field of the invention relates to the field of standard cells and their design, and in particular to addressing non-uniform boundary conditions in such cells.
2. Description of the Prior Art
In the design of semiconductor integrated circuits, circuit designers commonly use what are known as standard cells to achieve a particular logical function. Standard cells are essentially pre-designed layouts of transistors that are wired to perform a certain type of logical function. They are designed such that their boundary conditions are standard so that they can interact with each other in a manufacturable way and thus, any standard cell can be placed on any placement site in a standard cell block. In this way a designer can position the standard cells required for a system in any appropriate placement site without needing to worry about interactions with a neighbouring cell.
As standard cells are getting smaller in the portion of the standard cell area that has to be carefully controlled to insure manufacturability has grown to the point where many designs now depend upon strict uniformity to insure manufacturability. This has lead to an increase in the cell size and greater inefficiencies in the cell.
It would be desirable to produce standard cells that are compatible with each other such that they can be placed at any standard cell placement site, next to any other standard cell, even when these standard cells have a reduced area allowed by less uniformity at the boundaries.